1. Field of the Invention
The present invention relates to a cleaning method and device for an objective lens of an optical pick-up of an optical disc device.
2. Description of Related Art
With optical disc devices that record or playback data to or from an optical disc medium such as an optical disc or magneto-optical disc etc. using an optical pick-up, if dust or tar from tobacco smoke etc. becomes attached to the surface of an objective lens of an optical pick-up and accumulated, transmissivity of an optical beam may deteriorate, which may be a substantial hindrance to the precision of recording (writing) and/or playback (reading) of data. This is particularly marked in optical disc devices for use with vehicles. It is therefore necessary for the surface of an objective lens of an optical pick-up of such optical disc device to be periodically cleaned.
When cleaning the surface of objective lenses of optical discs for playback use of CD's etc. of the related art, it has been necessary to use a commercial disc-type cleaner or to disassemble the optical disc device and then clean the pick-up. However, with optical disc devices for recording/playback such as DVD's, it is not possible to use a disc-type pick-up cleaner and it has therefore been necessary to disassemble a device at the time of cleaning.
In recent years, a method has been invented for periodically cleaning an objective lens where a cleaning disc with a cleaning brush (brush-filled) attached to a lower surface is loaded on a turntable and is rotatably driven by the turntable so that dust that has accumulated at the surface of the objective lens is removed by the cleaning brush of the cleaning disc (for example, Japanese Patent Application Publication No. 2002-92920).
Further, a cleaning method has also been invented where a cleaning brush is arranged midway in the path of an optical pick-up when the optical pick-up is going from the lower side to the upper side of an optical disc. The objective lens then comes into contact with the cleaning brush and dust that has accumulated at the surface of the objective lens is then cleaned off by the cleaning brush (for example, Japanese Patent Application Publication No. Hei. 06-111352).
Further, a lens cover having a large surface area may also be fitted in a freely rotating manner to the outer periphery of a rotating shaft of a spindle motor. At the time of recording/playback of an optical disc, a turntable is then rotatably driven in a predetermined direction by the rotating shaft of the spindle motor and the lens cover is rotated from a position covering the top of an objective lens to a retraction position so as to open up the objective lens. On the other hand, a method (for example, Japanese Patent Laid-open Publication No. 07-235074) has also been invented where the spindle motor is temporarily rotatably driven in a direction opposite to the predetermined direction after recording or playback of the optical disc. The lens cover is then rotated so as to go from the retraction position to the position covering the objective lens so as to make it difficult for dust to become attached to and accumulate at the surface of the objective lens.
However, cleaning methods for objective lenses using pick-up cleaners involve a great deal of work. Further, with methods of cleaning involving cleaning discs, cleaning brushes and lens covers etc or methods where dedicated mechanisms for dust-proofing use etc. are added, the number of parts and number of assembly steps increase, and this causes increase in cost of the optical devices. In particular, with the method where an objective lens is cleaned using a cleaning disc, it is necessary to load and unload a cleaning disc every time cleaning takes place, which is an extremely troublesome operation.